We (Array Science, LLC) propose to perform detailed research and development of our patent-pending method and instrument for high-yield production of tissue microarrays (TMAs). Our approach to TMA production is novel in leveraging the liquid phase of standard histologic embedding media such as paraffin, and in so doing we achieve unprecedented levels of utilization of precious biological tissue sources. The outcome of this technique has proven highly beneficial in cancer diagnostics, where it has produced over 1.3 million TMA sections for on-slide controls in a major immunohistochemistry (IHC) laboratory, and in IHC proficiency testing, where we have achieved new levels of yield as a supplier to the College of American Pathologists. Whereas conventional TMA production methods yield 100-300 slides per TMA block, our method routinely produces 1500 slides per TMA block, with highly reduced levels of waste of source tissue. Theoretical yield is still up to twice our currenty achieved level, with two essential elements necessary for repeatably achieving maximum yields and realizing the full potential benefits of our method. First, a deeper understanding is required of the thermal-fluid dynamics and tissue mechanics that underly our method and dictate the success of a high-yield TMA block in histology. Concurrently and in light of this improved understanding, design changes to the instrument are required that will handle fluid and heat flow somewhat differently than in our instruments to date. Automation and computer control of several specific functions in the instrument are an important part of the effort, and will serve asa technical bridge between Phase I and Phase II. In the proposed research, a systematic study will be performed to recover half to all of the remaining available yield, utilizing (a) microCT scanning for non-destructive TMA block testing (virtual histology) combined with automated image analysis to correlate TMA section flaws with artifacts of the TMA block building process; (b) method and instrument refinements to better control the fluid and solid mechanics of the two-phase block building process; (c) automation of the Array Science process for improved uniformity and portability of the technology to new users. The versatility of the Array Science method will also be systematically studied as regards tissue source preparations, from conventional (FFPE block coring) methods, to highly fragmented solid tissue in liquid suspension, to the use of cell culture material. Quantitative comparative analyses of microCT slice images and micrographs of their corresponding histologic sections, and section yield measurements in histology, hold promise as a novel and powerful validation of microCT as a nondestructive virtual histology to achieve definitive conclusions about sensitivity and control of the high-yield TMA construction method.